refactor(core): Remove unused library_id field from SdPath

The library_id field in SdPath was not being used in any file operations
and didn't make sense as part of the core path abstraction. Library context
is better handled at higher levels (events, services) rather than being
embedded in every path reference.

Changes:
- Remove library_id field from SdPath struct
- Remove with_library() constructor method
- Update all constructors and methods to not reference library_id
- Update SdPathSerialized to match
- Update all documentation examples and references

This simplifies SdPath to focus purely on cross-device file path
representation with just device_id and path fields.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

core-new/README.md

@@ -70,7 +70,6 @@ The foundation for virtual distributed file systems:
 pub struct SdPath {
     device_id: Uuid,            // Which device
     path: PathBuf,              // Path on that device
-    library_id: Option<Uuid>,   // Optional library context
 }
 
 impl SdPath {

core-new/docs/design/CROSS_PLATFORM_COPY_AND_VOLUME_AWARENESS.md

@@ -231,7 +231,6 @@ pub enum CopyResult {
 pub struct SdPath {
     pub device_id: Uuid,        // ❌ Stored - should be computed
     pub path: PathBuf,
-    pub library_id: Option<Uuid>,
 }
 ```
 
@@ -243,9 +242,6 @@ pub struct SdPath {
 pub struct SdPath {
     /// The local path - this is the only stored data
     pub path: PathBuf,
-    
-    /// Optional library context
-    pub library_id: Option<Uuid>,
 }
 
 /// Extended path information - computed at runtime
@@ -263,7 +259,6 @@ pub struct SdPathInfo {
 #[derive(Serialize, Deserialize)]
 pub struct SdPathSerialized {
     pub path: PathBuf,
-    pub library_id: Option<Uuid>,
     // Note: device_id and volume info NOT serialized
 }
 
@@ -314,7 +309,6 @@ impl SdPath {
 pub struct SdPathRemote {
     pub device_id: Uuid,          // Required for remote paths
     pub path: PathBuf,
-    pub library_id: Option<Uuid>,
     pub last_known_volume: Option<VolumeFingerprint>,
 }
 ```

core-new/docs/design/DESIGN_FILE_DATA_MODEL.md

@@ -120,13 +120,12 @@ How SdPath is stored in the database:
 struct SdPathSerialized {
     device_id: Uuid,
     path: String,               // Normalized path
-    library_id: Option<Uuid>,
 }
 
 // In the database, this could be:
-// - Three columns: device_id, path, library_id
-// - Or JSON: {"device_id": "...", "path": "...", "library_id": null}
-// - Or a custom format: "device_id://path" or "library_id/device_id://path"
+// - Two columns: device_id, path
+// - Or JSON: {"device_id": "...", "path": "..."}
+// - Or a custom format: "device_id://path"
 ```
 
 ### 5. Location (Enhanced)

core-new/docs/design/DOMAIN_MODELS_README.md

@@ -10,7 +10,7 @@ The foundation of the VDFS. Represents any file or directory that Spacedrive kno
 ```rust
 let entry = Entry {
     id: Uuid::new_v4(),
-    sd_path: SdPathSerialized { device_id, path, library_id },
+    sd_path: SdPathSerialized { device_id, path },
     name: "vacation.jpg",
     kind: EntryKind::File { extension: Some("jpg") },
     metadata_id: metadata.id,  // ALWAYS has metadata!

core-new/src/domain/entry.rs

@@ -79,9 +79,6 @@ pub struct SdPathSerialized {
 
     /// Normalized path on that device
     pub path: String,
-
-    /// Optional library context
-    pub library_id: Option<Uuid>,
 }
 
 impl SdPathSerialized {
@@ -90,7 +87,6 @@ impl SdPathSerialized {
         Self {
             device_id: sdpath.device_id,
             path: sdpath.path.to_string_lossy().to_string(),
-            library_id: sdpath.library_id,
         }
     }
 
@@ -99,7 +95,6 @@ impl SdPathSerialized {
         SdPath {
             device_id: self.device_id,
             path: self.path.clone().into(),
-            library_id: self.library_id,
         }
     }
 }

core-new/src/shared/types.rs

@@ -20,10 +20,6 @@ pub struct SdPath {
 
     /// The local path on that device
     pub path: PathBuf,
-
-    /// Optional library context
-    /// If None, uses the current active library
-    pub library_id: Option<Uuid>,
 }
 
 impl SdPath {
@@ -32,25 +28,15 @@ impl SdPath {
         Self {
             device_id,
             path: path.into(),
-            library_id: None,
         }
     }
 
-    /// Create an SdPath with a specific library
-    pub fn with_library(device_id: Uuid, path: impl Into<PathBuf>, library_id: Uuid) -> Self {
-        Self {
-            device_id,
-            path: path.into(),
-            library_id: Some(library_id),
-        }
-    }
 
     /// Create an SdPath for a local file on this device
     pub fn local(path: impl Into<PathBuf>) -> Self {
         Self {
             device_id: get_current_device_id(), // Get the current device ID
             path: path.into(),
-            library_id: None,
         }
     }
 
@@ -87,7 +73,6 @@ impl SdPath {
         self.path.parent().map(|p| SdPath {
             device_id: self.device_id,
             path: p.to_path_buf(),
-            library_id: self.library_id,
         })
     }
 
@@ -96,7 +81,6 @@ impl SdPath {
         SdPath {
             device_id: self.device_id,
             path: self.path.join(path),
-            library_id: self.library_id,
         }
     }
 
@@ -191,7 +175,6 @@ mod tests {
 
         assert_eq!(path.device_id, device_id);
         assert_eq!(path.path, PathBuf::from("/home/user/file.txt"));
-        assert_eq!(path.library_id, None);
     }
 
     #[test]